The present invention relates to a closure for a container used in the transfer of materials or components between a contained isolation or clean-room process area and a non-sterile outside environment.
Transfers of sterilised materials between sterile or clean areas via the outside environment are routinely made in industries such as the pharmaceuticals, medical devices, biotechnology and food industries. Typically, a container or bag, the interior of which is sterile, is offered up to and coupled with a port in a wall of the process area. After conducting a sterilising cycle to sterilise the interface between the container and the port, a door in the port is opened to permit an operator located within the process area to gain access to the container and to remove a cap or lid from the container, thereby enabling the sterile interior of the container to be charged with sterile materials, or to permit sterile materials to be unloaded from the container into the process area.
Typically, the cap or lid of the container comprises a flexible foil which is sealed over the mouth of an opening provided in the container. The operator may remove the foil manually by punching it to rupture the foil, then pushing the broken foil pieces toward the rim or mouth to provide free access to the container interior via the mouth. Alternatively, the operator may use a sharp instrument to cut through the foil. Both methods are likely to generate some non-viable particulate material, which may enter the process area, contrary to good manufacturing practice codes in these industries. Both methods are also susceptible to causing perforation to be made in the operator's gloves, which could introduce viable particulate into the system, compromising the cleanliness of the process area. To avoid these problems, the foil may be provided with a tab which can be grasped by the operator to assist him in peeling the foil, in an unbroken state, from the container mouth. In such cases, care must be taken to ensure that whichever sterilizing means is used to sterilize the interface between the coupled container and dock is effective to sterilize all surfaces of the tab.
An effective coupling assembly for a container and a port is disclosed in WO96/21615 and comprises a collar of substantially tubular shape which docks with the port of a process area. The collar forms part of a transportable container. The port includes a door which opens inwardly into the process area. To the exterior facing side of the door are mounted ultraviolet (UV) or pulsed white light emitting sources which emit radiation at a frequency effective for sterilisation. On docking of the collar and port, a sealed chamber is established between the port and the collar and this chamber is sterilize by activation of the UV or pulsed white light lamps for a sufficient amount of time. Thereafter, the port door is opened and a foil covering the mouth of the collar can be removed to enable materials or components to be transferred between the container and process area. It will be appreciated that the foil will have a pull tab to facilitate its removal and that it is a matter of some difficulty to arrange the tab in such a way as to ensure that none of its surfaces are shadowed from the sterilizing radiation. Such shadowing may occur as illustrated in prior art Figure A, which shows a peel-off foil F covering the mouth M of the collar C of a container (not shown). The foil F is sealed to the mouth M by glue G. The foil F overlaps the mouth M at O, the overlap providing a grippable area which an operator can grasp to remove the foil F. However, it will be appreciated that while the upper surface F' of the foil lies in the direct line of the sterilising radiation (shown by the arrows), the underside surface F" of the overlapped portion is shadowed from the sterilising radiation by the foil F itself and this area constitutes a potential source of viable contamination of the entire process area once the foil has been peeled away.